Field of the Invention
The present invention relates to a structure of a muffler which reduces exhaust noise of exhaust gas, and more particularly, to a structure of a muffler for a vehicle, which is capable of improving output by reducing back pressure, and capable of generating more sporty exhaust sound by emphasizing a middle to low frequency sound while suppressing high frequency sound.
Description of Related Art
An exhaust system mounted in a vehicle is an apparatus which discharges exhaust gas generated in an engine to the outside, and reduces exhaust noise.
A typical exhaust system for a vehicle includes an exhaust manifold which is connected to cylinders in an engine, a catalyst converter (1 in FIG. 1) which converts hazardous substances in exhaust gas by using catalysts, a muffler (main silencer) (4 in FIG. 1) which has an interior divided by a plurality of baffles so as to induce expansion of exhaust gas, and thus reduces exhaust sound by using reflection or resonance of acoustic waves, a sub-silencer (2 in FIG. 1) which serves to assist the muffler in order to improve resonance properties of an exhaust noise system, and end pipes (3 in FIG. 1) which extend from the muffler and finally discharge exhaust gas.
Among the above components, the muffler is configured such that a plurality of pipes and the plurality of baffles are mounted in a housing formed in a cylindrical shape having a predetermined size so as to reduce exhaust noise by inducing expansion of exhaust gas, resonance, and absorbing noise when exhaust gas flows.
Meanwhile, the shape and the disposition structure of the muffler vary in accordance with the number and the disposition structure of the end pipes which extend from the muffler and discharge exhaust gas to the outside.
A transverse structure (in which the muffler is disposed in a vehicle width direction), among various disposition structures of the muffler, is configured as illustrated in FIG. 1 in order to implement sporty sound and solve a problem of thermal damage. That is, in a structure in the related art, an interior of a housing 5 is divided into first to fifth chambers 6a, 6b, 6c, 6d, and 6e by four baffles 5a, an inlet pipe 8 through which exhaust gas flows in is connected to the third chamber 6c, a first pipe 9a is positioned to penetrate the baffles 5a so that both ends of the first pipe 9a are positioned in the third chamber 6c and the fifth chamber 6e, respectively, and a second pipe 9b is mounted such that one side end of the second pipe 9b is positioned in the fifth chamber 6e and the other side end of the second pipe 9b extends to the end pipes 3 outside the housing 5. Further, exhaust gas discharged from the inlet pipe 8 flows into the fifth chamber 6e through the first pipe 9a and then is discharged to the outside of the housing 5 from the fifth chamber 6e through the second pipe 9b. Further, acoustic absorbents are disposed in the first chamber 6a, the second chamber 6b, and the fourth chamber 6d, respectively, and through holes through which exhaust gas flows in and out are formed in the first pipe 9a and the second pipe 9b at the points with which the acoustic absorbents are in direct contact, such that exhaust noise is reduced while exhaust gas is discharged to the outside.
However, in the case of the structure in the related art, there are problems in that the structure is disadvantageous when implementing a sporty sound and back pressure is set to be high.
That is, in general, in order to implement an optimum sporty sound, it is important to maximally reduce high frequency noise which is rough to hear, and to appropriately maintain a rumble sound within a low or middle frequency region. However, in the case of the structure in the related art, exhaust gas flows into the third chamber 6c and then is discharged through the fifth chamber 6e (a flow path of exhaust gas is lengthened), and as a result, the structure in the related art cannot increase noise in a particular RPM band but is suitable to reduce overall noise. In addition, because a vehicle, which requires a sporty tone, also requires high engine performance, it is essential to reduce back pressure in order to satisfy engine performance. However, in a single tip structure (which is configured such that a single pipe extends outward from the muffler housing as illustrated in FIG. 1), the amount of exhaust gas that can be discharged is restricted, and as a result, there is a problem in that it is difficult to reduce back pressure and satisfy engine performance.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.